Takahiro Suzuki | 241c10e | 2020-12-17 20:17:57 +0900 | [diff] [blame^] | 1 | // Copyright 2018 The Go Authors. All rights reserved. |
| 2 | // Use of this source code is governed by a BSD-style |
| 3 | // license that can be found in the LICENSE file. |
| 4 | |
| 5 | // Package errors implements functions to manipulate errors. |
| 6 | package errors |
| 7 | |
| 8 | import ( |
| 9 | "errors" |
| 10 | "fmt" |
| 11 | |
| 12 | "google.golang.org/protobuf/internal/detrand" |
| 13 | ) |
| 14 | |
| 15 | // Error is a sentinel matching all errors produced by this package. |
| 16 | var Error = errors.New("protobuf error") |
| 17 | |
| 18 | // New formats a string according to the format specifier and arguments and |
| 19 | // returns an error that has a "proto" prefix. |
| 20 | func New(f string, x ...interface{}) error { |
| 21 | return &prefixError{s: format(f, x...)} |
| 22 | } |
| 23 | |
| 24 | type prefixError struct{ s string } |
| 25 | |
| 26 | var prefix = func() string { |
| 27 | // Deliberately introduce instability into the error message string to |
| 28 | // discourage users from performing error string comparisons. |
| 29 | if detrand.Bool() { |
| 30 | return "proto: " // use non-breaking spaces (U+00a0) |
| 31 | } else { |
| 32 | return "proto: " // use regular spaces (U+0020) |
| 33 | } |
| 34 | }() |
| 35 | |
| 36 | func (e *prefixError) Error() string { |
| 37 | return prefix + e.s |
| 38 | } |
| 39 | |
| 40 | func (e *prefixError) Unwrap() error { |
| 41 | return Error |
| 42 | } |
| 43 | |
| 44 | // Wrap returns an error that has a "proto" prefix, the formatted string described |
| 45 | // by the format specifier and arguments, and a suffix of err. The error wraps err. |
| 46 | func Wrap(err error, f string, x ...interface{}) error { |
| 47 | return &wrapError{ |
| 48 | s: format(f, x...), |
| 49 | err: err, |
| 50 | } |
| 51 | } |
| 52 | |
| 53 | type wrapError struct { |
| 54 | s string |
| 55 | err error |
| 56 | } |
| 57 | |
| 58 | func (e *wrapError) Error() string { |
| 59 | return format("%v%v: %v", prefix, e.s, e.err) |
| 60 | } |
| 61 | |
| 62 | func (e *wrapError) Unwrap() error { |
| 63 | return e.err |
| 64 | } |
| 65 | |
| 66 | func (e *wrapError) Is(target error) bool { |
| 67 | return target == Error |
| 68 | } |
| 69 | |
| 70 | func format(f string, x ...interface{}) string { |
| 71 | // avoid "proto: " prefix when chaining |
| 72 | for i := 0; i < len(x); i++ { |
| 73 | switch e := x[i].(type) { |
| 74 | case *prefixError: |
| 75 | x[i] = e.s |
| 76 | case *wrapError: |
| 77 | x[i] = format("%v: %v", e.s, e.err) |
| 78 | } |
| 79 | } |
| 80 | return fmt.Sprintf(f, x...) |
| 81 | } |
| 82 | |
| 83 | func InvalidUTF8(name string) error { |
| 84 | return New("field %v contains invalid UTF-8", name) |
| 85 | } |
| 86 | |
| 87 | func RequiredNotSet(name string) error { |
| 88 | return New("required field %v not set", name) |
| 89 | } |